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OSPF stub, totally stubby and NSSA areas
Enterprise Advanced 4 devices 4 checked tasks 100 points Plan lab
Area 1 is a branch with one way out: make it totally stubby so R1 carries a default and nothing else. Area 2 has an ASBR of its own, so it cannot be a stub — make it an NSSA, and watch its external arrive as N2 and leave the ABR as E2. You build it in a browser, type real commands at each device, and every task below is
checked against the running configuration — so you find out it is wrong before anybody else does.
Open this lab in the simulator
The simulator runs in your browser with nothing to install. This lab is part of the full simulator: open it free for 7 days with a new account, then with a plan. It needs an account, which keeps your progress.
The scenario
Area 1 is a branch with one way out: make it totally stubby so R1 carries a default and nothing else. Area 2 has an ASBR of its own, so it cannot be a stub — make it an NSSA, and watch its external arrive as N2 and leave the ABR as E2.
Your role: a network engineer on the enterprise team. Level: Advanced Done when: all 4 goals show as passed (100 points).
Network status
Devices: 4 routers, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. R1-Branch starts with addresses (G0/0 10.0.12.1/24, L0 1.1.1.1/32) and OSPF 1 already configured. R2-ABR1 starts with addresses (G0/0 10.0.12.2/24, G0/1 10.0.23.2/24) and OSPF 1 already configured. R3-ABR2 starts with addresses (G0/1 10.0.23.3/24, G0/0 10.0.34.3/24) and OSPF 1 already configured. R4-ASBR starts with addresses (G0/0 10.0.34.4/24) and static routes, OSPF 1 already configured. Known problems
The network worked and now does not: the scenario above says what users report. The cause is a configuration fault, not a cable. Find it with show commands (interfaces, routes, neighbours, running-config) before you change anything; fix only what is wrong. Goals
Area 1 is totally stubby on its ABR (20 pts) R1 carries an inter-area default and no other inter-area or external route (25 pts) Area 2 is an NSSA and R3 sees R4’s external as O N2 (30 pts) The backbone sees it translated to O E2 (25 pts) The activity, in order
Area 1 is totally stubby on its ABR Why: Each goal is a state the lab can check on the running device. Verify with: show running-config R1 carries an inter-area default and no other inter-area or external route Why: The code tells you HOW a route was learned, which tells you which process to look at if it is wrong. Verify with: show ip route Area 2 is an NSSA and R3 sees R4’s external as O N2 Why: The code tells you HOW a route was learned, which tells you which process to look at if it is wrong. Verify with: show ip route The backbone sees it translated to O E2 Why: The code tells you HOW a route was learned, which tells you which process to look at if it is wrong. Verify with: show ip route Tips
Work in the order given: later goals depend on the earlier ones. After every change, run the verify command before moving on; do not guess. Stuck? Read the verify output first. It names the interface, neighbour or route that is wrong. Why this matters
Area 1 is a branch with one way out: make it totally stubby so R1 carries a default and nothing else. Area 2 has an ASBR of its own, so it cannot be a stub — make it an NSSA, and watch its external arrive as N2 and leave the ABR as E2.
What you will be able to do
Area 1 is totally stubby on its ABR
R1 carries an inter-area default and no other inter-area or external route
Area 2 is an NSSA and R3 sees R4’s external as O N2
The backbone sees it translated to O E2
The network
ISR 2911 — 4 devices in all, already cabled.
Gi0/0 10.0.12.1/24 Gi0/0 10.0.12.2/24 Gi0/1 10.0.23.2/24 Gi0/1 10.0.23.3/24 Gi0/0 10.0.34.3/24 Gi0/0 10.0.34.4/24 R1-Branch R2-ABR1 R3-ABR2 R4-ASBR Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
R1-Branch ISR 2911 configure it R2-ABR1 ISR 2911 configure it R3-ABR2 ISR 2911 configure it R4-ASBR ISR 2911 configure it
Cabling
R1-Branch Gi0/0 ↔ R2-ABR1 Gi0/0 R2-ABR1 Gi0/1 ↔ R3-ABR2 Gi0/1 R3-ABR2 Gi0/0 ↔ R4-ASBR Gi0/0
What is configured at the start
These are already configured when the lab opens — including, where this is a troubleshooting lab, the fault itself:
R1-Branch interface g0/0
ip address 10.0.12.1 255.255.255.0
no shutdown
exit
interface lo0
ip address 1.1.1.1 255.255.255.255
no shutdown
exit
router ospf 1
router-id 1.1.1.1
network 10.0.12.0 0.0.0.255 area 1
network 1.1.1.1 0.0.0.0 area 1 R2-ABR1 interface g0/0
ip address 10.0.12.2 255.255.255.0
no shutdown
exit
interface g0/1
ip address 10.0.23.2 255.255.255.0
no shutdown
exit
router ospf 1
router-id 2.2.2.2
network 10.0.12.0 0.0.0.255 area 1
network 10.0.23.0 0.0.0.255 area 0 R3-ABR2 interface g0/1
ip address 10.0.23.3 255.255.255.0
no shutdown
exit
interface g0/0
ip address 10.0.34.3 255.255.255.0
no shutdown
exit
router ospf 1
router-id 3.3.3.3
network 10.0.23.0 0.0.0.255 area 0
network 10.0.34.0 0.0.0.255 area 2 R4-ASBR interface g0/0
ip address 10.0.34.4 255.255.255.0
no shutdown
exit
ip route 192.168.40.0 255.255.255.0 Null0
router ospf 1
router-id 4.4.4.4
network 10.0.34.0 0.0.0.255 area 2
redistribute static subnets Tasks, and how each one is checked
Every task is decided by reading the live network — a neighbour in FULL, a ping that succeeds, a line in the running configuration — not by looking for a keyword you typed. The same command shows you what the lab sees.
# Task Pts How to verify it yourself
1 Area 1 is totally stubby on its ABR 20 Checked automatically against the device’s live state (ospfAreaType). 2 R1 carries an inter-area default and no other inter-area or external route 25 On R1-Branch: show ip route lists 0.0.0.0/0 with code O IA. and On R1-Branch: show ip route does not list 10.0.34.0/24. and On R1-Branch: show ip route does not list 192.168.40.0/24. 3 Area 2 is an NSSA and R3 sees R4’s external as O N2 30 On R3-ABR2: show ip route lists 192.168.40.0/24 with code O N2. 4 The backbone sees it translated to O E2 25 On R2-ABR1: show ip route lists 192.168.40.0/24 with code O E2.
Stuck? Ask the coach
Tell the coach what you see or what you tried. It gives you a hint, not the answer, the way a senior engineer would. Included with a free trial or any plan.
Ask the coach
Reference solution
Try it yourself first — the lab checks your work either way. This is one configuration that makes every task pass, device by device:
R1-Branch router ospf 1
area 1 stub R2-ABR1 router ospf 1
area 1 stub no-summary R3-ABR2 router ospf 1
area 2 nssa R4-ASBR router ospf 1
area 2 nssa Where this is examined
This lab practises these topics in the zNetLaB certification courses:
Related labs
Where to start
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